People and objects gain or lose heat through four mechanisms: conduction, convection, evaporation, and radiation. These mechanisms affect whether an office building, a server farm, an airplane factory, an airline hangar, maintenance hangar, or other form of enclosure (inclusive of complete and partial enclosures) is maintained at a tolerable temperature during hot weather in summer, or at other locations having high temperatures. In each instance, the ability to cool the object, such as a building, may be inhibited through exposure to direct and reflected (indirect) sunlight. If direct and indirect sunlight are reduced, the ability to effectively and economically keep the enclosure cool increases.
Direct heating, as applied to sunlight, refers to sunlight (a) arriving directly at a building's surface from the sun and (b) getting absorbed as heat at that surface. Indirect heating occurs when sunlight is reflected or scattered from a building's outer wall, and then does one of the following:    1. Gets absorbed by a nearby building, person, or vehicle that is to be kept cool (e.g., an airliner parked near a terminal building);    2. Gets reflected from nearby terrain, buildings, or vehicles back to the original building, where it is absorbed as heat; or    3. Gets absorbed by terrain near the building, e.g., parking lots, lawns, or airport tarmac. This heats the nearby portion of the Earth's surface. That heated terrain, which may include man-made objects on the terrain, increases the heat load of the original building by three mechanisms: (a) infrared radiation, (b) convective heating as air from the hot surface rises and blows against the building, thereby transferring heat to the outer wall or window, and (c) air from the hot surface rising and getting pulled into a heat exchanger for the building's air-conditioner, thereby reducing the air conditioner's cooling efficiency.
A number of approaches have been taken to optimize cooling of an enclosure, such as a building. One approach includes applying white paint to the roof and outer walls of the building to reflect sunlight. However, white paint scatters sunlight onto nearby surfaces that, in turn, become hotter and contribute to indirect heating of the building.
Another approach includes applying reflective coatings on building windows to reflect sunlight via specular reflection. Depending on the coating, it may also reduce absorption of infrared heat. However, reflective window coatings also reflect sunlight onto terrain near the building. This increases indirect heating of the building by backscattered sunlight and by convection.
Insulation may be installed in building walls as another approach to reduce heat transferred from the building's outer surface to the building's interior by conduction through the walls, convection between layers of the walls, and/or radiation between layers of the walls. However, insulation does not reduce temperatures outside the building, which rise in sunlight. Therefore, insulation does not address problems associated with indirect heating and lost air conditioner efficiency.
One or more of the foregoing may be used in a given building. However, in each instance, the various problems associated with each individual approach remain.